First 20p chamber reaming

**223Randy** · 07-20-2017, 10:02 PM

The 20P reamer looks so fragile. Doing my first 20P chamber and i am going very slowly, the flutes on the start end of the 20p reamer are tiny and fill up quickly so i am going very slowly.
I am about 1/3 depth so far and seems like it is taking forever. my setup is in an older southbend heavy 10 with a vfd and using the backgear running about 30 rpms seems that about .015 depth and the flutes are full. chamber looks great so far so i guess i will just keep going very slow and will get to the proper depth in a bit.
I indicated the bore in on both ends Chuck and Spider to less than .0005 before starting

Does this sound about right to the guys that have done this?

Thanks

**sharpshooter** · 07-20-2017, 11:19 PM

The flutes on .20 and .17 cal reamers are pretty shallow and don't allow a lot of feed rate, but you need to speed it up to about 90 rpm. This will make for smaller chips that will flow out of the flutes faster.
I use a muzzle flush system to pump cutting oil towards the cutter and I usually run a t 130 rpm. If you have a good reamer, the chips will flow out at such a constant rate that you'll only have to withdraw the reamer a few times to clear it.

**223Randy** · 07-24-2017, 10:54 PM

Thanks Sharpshooter,
i speeded it up to 50 rpms and used lots of oil, slow but firm feed and finished it up without any issues this eve. Now i have to decide what crown and what finish grit to use on the OD of the SST barrel.
Looking great so far!

Randy

**223Randy** · 08-01-2017, 08:11 PM

Well finally finished it up, used 400 grit on OD and then crowned with a recessed target crown. Assembled it and took her out for a trial run. Loaded up some light loads of 34gr dogtown bullets and fired one into the hill with a string. Then i settled in and put 6 rounds in a dime sized group, all about 1" left of the target center. I made a 1" adjustment and fired the 7th round dead center of the bulls eye.
Since my longest shots are almost always 200 yrds or less, it should be good to go now. First impressions of this Green Mountain barrel are that it can probably out shoot me!